1. Field
One embodiment of the invention relates to an information processor that supplies power to an electronic device connected thereto.
2. Description of the Related Art
Recently, a universal serial bus (USB) (Registered Trademark) specification is widespread, and it has become possible to connect various electronic devices to an information processor such as a personal computer (PC) through the USB. Such electronics devices (hereinafter, referred to as USB devices) are, for example, a keyboard, a mouse, a portable music player having a built-in battery configured to be charged while connected to the PC, and the like.
Besides the widespread of the electronic device having the built-in battery, there is recently known a PC that can charge the electronic device not only during the time when the power of the PC is on (referred to as a normal operation mode) but also during the time when the power thereof is off (referred to as a standby mode). Japanese Registered Utility Model No. 3127705 discloses such PC that switches between a circuit module and a power supply module depending on whether the PC is in the normal operation mode or in the standby mode, so that even in the standby mode the electronic device connected to the PC can be supplied power directly from the power supply module.
Recently, there is known a USB device that is charged only when a differential signal pair transmitted through a pair of data signal lines D+ and D− of the USB has a predetermined voltage difference. Therefore, when the USB device is to be charged, the PC outputs the differential signal pair having the predetermined voltage difference to the USB device.
However, different types of USB devices normally employ different charging specifications, each of which corresponds to different voltage differences (hereinafter, referred to as voltage levels). Hence, the conventional PC cannot charge all of the plurality of USB devices employing different battery charging specifications.
The invention is provided in view of the forgoing, and it is an object of the invention to provide an information processor capable of appropriately charging each of a plurality of electronic devices employing different charging specifications.